1. Field of the Invention
The invention relates to an optical device and a manufacturing method thereof. More particularly, the invention relates to an optical device including an optical element and a wiring board having the optical element mounted thereon, in which an electrically connected portion of the optical element and the wiring board is resin-sealed, and a manufacturing method of the optical device.
2. Related Art
Optical devices having an optical semiconductor device, such as a solid state imaging element and an LED (Light Emitting Diode), mounted on a wiring board have been known in the art. An example of such an optical device has a hollow package structure in which a light-transmitting substrate is provided over an optical function surface in order to protect the optical function surface (for example, see Japanese Laid-Open Patent Publication Nos. 2003-332542 and 2006-303481). In another example of such an optical device, a transparent resin is applied to an optical function surface (for example, see Japanese Laid-Open Patent Publication No. 9-298249).
However, such optical devices cannot be used to receive or emit blue-violet laser light having a wavelength as short as 405 nanometers (nm) because transparent resin discolors with time and the transmittance changes. Such a change in transmittance does not occur when a glass plate with a special coating is used as a light-transmitting substrate. However, such a glass plate is very expensive, and the manufacturing cost is increased.
In view of the above problems, Japanese Laid-Open Patent Publication No. 2006-186288 proposes an optical function element module. In this optical function element module, a bank for damming up a liquid sealing resin is provided around an optical function element on a substrate on which the optical function element is mounted. The liquid sealing resin is dropped between the optical function element and the bank to fill the space between the optical function element and the bank with the liquid sealing resin. A package component member has a light-transmission hole corresponding to an optical function portion of the optical function element. The package component member is made in contact with the sealing resin by placing the package component member on the bank so that the light-transmission hole faces the optical function portion of the optical function element. The sealing resin is then cured to fix the package component member on the substrate, and the bank is cut off and removed at the end.
In manufacturing of the optical function element module described in Japanese Laid-Open Patent Publication No. 2006-186288, it is difficult to control dropping of the liquid sealing resin so as to form a desired amount of sealing resin with a desired shape only within a desired range. Moreover, the liquid sealing resin may be dropped onto the optical function portion when the liquid sealing resin is dropped between the optical function element and the bank. The liquid sealing resin may also flow onto the optical function portion when the package component member is placed on the bank. This results in reduction in yield. In order to reliably avoid such problems, the area of the optical function element needs to be increased to assure a sufficient distance between the end of the optical function element corresponding to the bank and the optical function portion. However, this makes it impossible to achieve size reduction which is one of the objects of Japanese Laid-Open Publication No. 2006-186288.
The invention is made in view of the above problems and it is an object of the invention to provide a small optical device having an exposed optical function region, which can be manufactured by a simple, low-cost method.